Even though it lacks some important features for now, Telegram Purple has some advantages over stand-alone solutions, like the ones mentioned above: since you can use it with Pidgin, you don't have to open multiple chat clients and you have all your contacts in a single list. And since it's under heavy development, we'll hopefully see some of these missing features implemented soon.

Tip: to use the Telegram iOS or Android Emojis, download them from HERE, copy the Emoji folder to ~/.purple/smileys/ and select the new smiley theme from the Pidgin preference (Themes > Smiley Theme).

Install Telegram Purple plugin for Pidgin

To make it easier to install in Ubuntu / Linux Mint (and derivatives), I've packaged Telegram Purple and uploaded it to the main WebUpd8 PPA. Add the PPA and install the plugin using the following commands:

Using Telegram Purple with Pidgin

Note: to be able to use any Telegram desktop client, you must firstly install the Telegram app on your mobile device.

Using Telegram Purple with Pidgin is pretty easy. After installing the plugin (see above), start Pidgin (restart it if it was already running) and from its menu select Accounts > Manager Accounts. Here, click "Add" and from the protocol drop-down list, select Telegram.

Next, enter your phone number under "Username" (including the country prefix) and click "Add":

The first time you add your Telegram account, a popup will be displayed, asking you to enter the Telegram code you've received via SMS: